“Before it was the logo of a globally popular football team, the three diamonds were the seal of a product which helped develop the foundation of many cities across the globe — steel. Like Pittsburgh and its residents, steel is strong,” he wrote in the Facebook post.

Reaction from the sports world

Steelers spokesman Burt Lauten tweeted that a moment of silence will be observed before the game.

The same observance was made Saturday night before Game 4 of the World Series in Los Angeles and before the NHL’s Toronto Maple Leafs vs. Winnipeg Jets game in Toronto.

On social media, Pittsburgh sports teams and their players stood with those mourning in their city.

We send our thoughts and prayers to those affected by this morning’s tragedy in Pittsburgh. We will continue to pray for everyone involved.